AC Th, Lvl III - 3rd Ed. Lesson 4: Electronic Circuit Test Instruments Quiz for Lesson 4
Two-wire solid-state switches connected in ? affect the operation of a load because of the voltage drop across the switches.
Series
The reason the current peak value in Display 2 is not equal to approximately 1.41 times the rms measured value is because the waveform is not a pure sine wave.
T
Manually operated switches include ? .
foot switches
The volts/division (volts per division) control selects the ? of the displayed waveform.
height
Calculate the signal attributes based on the information in the illustration.
0.008
In Display 1, the meter tells the time between the two cursors. What is time per division control setting (sec/div) of the meter?
0.5 sec/div
Calculate the signal attributes based on the information in the illustration.
125
Fundamental signal RMS voltage is ? .
14.14 V
If Input 1 on Display Screen 2 is 60 Hz, what is the frequency of Input 2?
180 Hz
Calculate the signal attributes based on the information in the illustration.
20
A ? solid-state switch draws operating current directly from a power source and does not allow the operating current to flow through the load.
3-wire
Calculate the signal attributes based on the information in the illustration.
42
Calculate the signal attributes based on the information in the illustration. (Round the FINAL answer to two decimal places.)
5.25
How many degrees out of phase are Input 1 and Input 2 on Display Screen 1?
90°
How is object vibration related to the type of sound produced by the object?
All of the above
? is the process of taking a small signal and increasing the size of the signal.
Amplification
What is the approximate root mean square value of Waveform 2 in Display 3?
Approximately 4.24 A
In Display 1, Cursor 2 is set to measure the running current of the motor. What is the running current (peak) of the motor?
Approximately 48A
In Display 2, what is the approximate peak current value?
Approximately 50 A
What is the root mean square voltage of Input 1 on Display Screen 1 when the volts/div setting is on 50?
Based on approximately 175 V peak voltage, approximately 124 V rms
What is the approximate root mean square value of Waveform 1 in Display 3?
Based on approximately 250 V peak voltage, approximately 177 V rms
? is the frequency that controls the number of times the solid-state switches in the inverter section of a Pulse Width Modulated (PWM) variable frequency drive turn on and turn off per second.
Carrier frequency
What type of voltage is Display 3 showing?
DC voltage
A frequency meter is a test instrument used to measure the frequency of a DC signal.
F
Frequency meters graphically show any distortion present in the circuit voltage.
F
Gain is the ratio of the amplitude of the input signal to the amplitude of the output signal.
F
Operating current is the minimum current that ensures proper operation of a solid-state switch.
F
The voltage limit of an oscilloscope equals 1/10th the normal rated voltage when a 10x probe is used.
F
? is the number of cycles per second of an AC sine wave.
Frequency
Determine whether the following NPN transistor is good, shorted, or open, based on the ohmmeter readings in the illustration. The solid probe leads represent the first reading. The dashed probe leads represent the second reading.
Good
In which two ways can a transistor be used?
I. and III.
The higher the carrier frequency to an AC motor, the closer the output sine wave is to a pure fundamental frequency sine wave and the cooler the motor operates.
It can increase the noise produced by the motor.
? bandwidth is the highest frequency an oscilloscope can capture in a single pass.
Real-time
? typically output sine waves, square waves, or triangular waves.
Signal generators
? is accomplished using test instruments to either measure an electronic signal already within a system or circuit or to measure an electronic signal intentionally injected into a system or circuit.
Signal tracing
The higher the sample rate of an oscilloscope, the more accurate the trace of the signal being tested.
T
A two-wire solid-state switch is also called a load-powered switch because the switch draws operating current from the power source and allows the operating current to return to the power source through the load.
T
An AC motor designed to operate at 60 hertz rotates more slowly when the frequency is less than 60 hertz and rotates faster when the frequency is above 60 hertz.
T
In a transistor, a very small current applied to one lead controls a large current flow through the other two leads.
T
The higher the carrier frequency to an AC motor, the closer the output sine wave is to a pure fundamental frequency sine wave and the cooler the motor operates.
T
Identify the waveform types and components in the illustration.
The correct answer is: Carrier signal → B, Waveform → C, Fundamental signal → A, Pulses → D
Identify the waveform terms in the illustration.
The correct answer is: Positive alternation → B, Periods → A, One cycle → E, Time → C, Negative alternation → D, Voltage or current → F
Identify the type of signal variation from the undistorted input with the appropriate oscilloscope trace in the illustration.
The correct answer is: → Temporary loss of signal, → Voltage amplitude change, → Voltage frequency change
Identify the type of signal variation from the undistorted input with the appropriate oscilloscope trace in the illustration.
The correct answer is: → Voltage with DC offset (DC in signal), → Signal gain, → Voltage with clipped wave (flat-topping)
A cycle is one complete wave of alternating positive and negative voltage or current. A(n) ? is one half of a cycle.
alternation
Meters designed to operate on circuits with solid-state devices include a bypass filter circuit to separate the power frequency from the ? frequency and display only the power frequency.
carrier
A ? is a thyristor that is triggered into conduction in only one direction and is suited for DC current use.
b.Silicon Controlled Rectifier (SCR)
? turn-on is a method of turning on a thyristor that occurs when a fast-rising voltage is applied across the terminals of a triac.
b.Static
In Display 1, Cursor 1 is set to measure the inrush current at the start of a motor. What is the peak starting current of the motor?
c.Approximately 48 A d.Approximately 96 A
A(n) ? is an acoustical unit used to measure the intensity (volume) of sound.
decibel
A ? is a special test instrument (DC voltmeter) that detects the presence or absence of a high or low signal.
digital logic probe
Digital circuits fail because the ? is lost somewhere between the circuit input and output stages.
digital signal
A(n) ? oscilloscope is an oscilloscope that displays two signal traces simultaneously.
dual-trace
Determine whether the output state is high or low, based on the input states and the logic functions in the illustrations.
high/energized
The larger the amplitude of a sound wave, the ? the sound produced.
louder
Determine whether the output state is high or low, based on the input states and the logic functions in the illustrations.
low/de-energized
Determine whether the following NPN transistor is good, shorted, or open, based on the ohmmeter readings in the illustration. The solid probe leads represent the first reading. The dashed probe leads represent the second reading.
open
Triacs should be tested under operating conditions using a(n) ? .
oscilloscope
Determine whether the following NPN transistor is good, shorted, or open, based on the ohmmeter readings in the illustration. The solid probe leads represent the first reading. The dashed probe leads represent the second reading.
shorted
To determine the frequency of the waveform, divide the ? into 1.
time period
On an oscilloscope, the horizontal (x) axis represents ? , and the vertical (y) axis represents ? of the voltage waveform.
time/amplitude
